Art of grinding



March 12, 1935. v ,'w BINNS 1,993,823

ART OF GRINDING Filed Dec. 31, 1951 Ja -5 M a W Patented Mar. 12, 1935ART GRINDING George W. Binns, Cincinnati, Ohio, assignor CincinnatiGrinders Incorporated, Cincinnati,

Ohio, a corporation of Ohio Application December 21, 1931, Serial No.582,292

3 Claims. (Cl. 51-278) This invention relates to improvements in the artof grinding and especially to improvements in a process or method ofgrinding.

An object of the invention is the provision of an improved process foraccurately finishing tapered articles such as mushroom typevalv'es andthe like.

Another object of this invention is the provision of an improved processfor finish grinding tapered valve seats and the like so that said valvesseat throughout, their area without being lapped or requiring thelapping in thereof.

A further object of the invention is the provision of an improvedprocess for producing tapered valve seats free from chatter and otherimperfections.

These and other objects are attained through the performance of theprocess diagrammatically depicted in the accompanying drawing anddescribed in the following specification and it is to be understood thatcertain deviations may be made in the steps of the process as heredescribed and illustrated within the scope of the appended claimswithout departing from or exceeding the spirit of the invention.

In the drawing:

Figure 1 is a diagrammatic elevational view of a mechanism forperforming one step of the process.

Figure 2 is a top plan view of the structure shown in Figure 1.

Figure 3 is a diagrammatic elevational view of a mechanism forperforming a subsequent step in the process.'

Figure 4 is a top plan view of the structure shown in Figure 3.

Figure 5 is a view illustrating a part of the mechanism shown in Figures3 and 4 as seen from line 5-5 of Figure-3 and forming a detail of theinvention.

In the past it has been customary to grind tapered valve seats and thelike at definite angles'of inclination to the axis of a part integraltherewith, such as the guiding stem of mushroom type valves. These facesor seats, however, frequently had imparted to them the out of roundness,chatter and other irregularities of either the said guiding stem; worksupport, chuck or other driving mechanism. This resulted in thenecessity of either lapping the valve seat prior to use or grinding thesaid seat into the body of the valve or other part with which itis to beused. By the present process or method it has been found that taperedvalve I seats may be produced having a full seat and requiring nofurther machining operation prior to their use. There has been chosen,and depicted in the drawing, the mushroom type of valve, as used inconnection with internal combustion engines, to illustrate the varioussteps of the process, but it is to be understood that the process may beemployed for grinding or finishing other types and kinds of work pieces.

The work piece 10 is first completely formed and its stem 11 finishground to provide an axis of rotation, the valve seat 12 is then roughand semi-finished ground in any desirable manner and by any suitableprocess. It has been found, however, that if the work piece 10 isfloated in the throat of a centerless grinder and the seat 12 then roughand semi-finished ground on a centerless grinder before the finalfinishing operation the valve is completed in an expeditious manner andat a minimum cost. The roughing and semi-finishing grinding operationsare illustrated in Figures 1 and 2. As there shown, the centerlessgrinder comprises a work rest blade 13 having a supporting inclined face14, inclining toward the active surface of a regulating wheel 15. Theangled top 14 of the blade 13 with the operative face of the regulatingwheel 15 form a workreceiving trough in which the stem 11 of the work isplaced. As will be noted from Figures 1 and 2, the axis of the work 10and regulating wheel 15 are in parallel vertical planes but that theaxis of the wheel 15 is canted or at an angle to the axis of the workwhereby the said wheel exerts a feeding component on the work tending toaxially shift same through the grinding throat. This movement of thework is arrested by a suitable stop 16 which engages the terminus of thestem 11. I I

In order to maintain proper frictional contact between the regulatingwheel 15 and the stem of the work, lateral or pressure rollers 17 areprovided. These rollers 17 are moimted in the end of an arm 18 which ispivoted at 19 to a suitable support or bracket. The arm 18 is actuatedin a clockwisedirection by a spring 20 whereby the rollers 17 yieldinglyhold'the work in engagement with the wheel 15. 1

It will be noted that the seat 12 is at an angle to the axis of thestem. Accordingly, there is provided a grinding wheel 21 rotatable aboutan axis which extends at the same angle to the axis of the work as theseat thereof. By this construction, a plane faced grinding wheel may beemployed instead of a grinding wheel having a contoured or angled facethereon which presents considerable difllculty in maintaining to thedesired form.

The work piece is subjected to several grinding operations as abovedescribed which provide a reasonable finish thereon but which in orderto be particularly useful must be lapped inor ground in to the part withwhich it is to be used. This may be caused partly by any chatter marksor out of roundness thatmay be in the stem 11 of the work. The sameresult is obtained if the work where mounted is a chuck or suspendedbetween supporting centers which may allow the work to spring under thepressure of the grinding wheel. This invention contemplates instead ofthe use of a lapping operation, a grinding operation which is far morerapid and considerably less expensive than the lapping or intergrindingoperation of the several parts. To this end the work piece is thenplaced in a second centerless grinder which likewise consists of a workrest blade or support 22 in close proximity to a regulating wheel 23. Agrinding wheel 24 is also provided, rotatable about an axis disposed atan angle so as to place the plane face of the wheel parallel with theface to be formed on the work. It will be noted that the regulatingwheel 23 is mounted for rotation about an axis extending parallel withthe axis of the workinstead of at an angle theretoas above described.From this it will be seen that the wheel 23 does not exert a feedcomponent on the work but merely effects and controls its rotation. Thework 10 is held in contact with the work rest blade or support 22 andwheel 23 by means 'of lateral or pressure rolls 25 in the same mannerthat the rollers 1'7 above described operate.

The work rest blade has secured to it a steady rest member 26 having atapered seat 27 at one end thereof conforming contragenerically to theseat 12 formed on the work. This ring like seat 2'7 extendssubstantially entirely around the seat of the valve being broken awayat28 an amount just suflicient to permit access of the grinding wheel 24with the said valve seat.

When the work reaches this stage of its manufacture, it is now necessaryonly to clean up the seat 12 by removing a very small amount of stock.For this reason no end stop is provided for the work, since it hasalready been reduced to the desired length. However, the work piece isyieldably axially ac uated relative to the grinding wheel and the steadyrest seat 27 so that the work, while it is rotating, will maintaincontact with the said steady rest seat 27 and the active face of thegrinding wheel 24. For effecting this axial shifting of the work thereis provided an end or terminal roller 29 rotatably carried by the end ofan arm 30 pivoted at 31 to a fixed portion of the machine. A spring 32has one end secured to the arm 30 and the other end to a fixed part ofthe machine which tends to oscillate the arm in a clockwise directionthereby shifting the work to the right as seen in Figure 5 into thecontact with the grinding wheel 24.

The seat 27 in contacting with the work substantially throughout itslength and breadth, except for the small area where it contacts with thewheel, efiectively prevents any lateral or radial movement of the workand insures same rotating about a definite unvarying axis. Thissteadying of the work prevents any chatter appearing in the seat so thata one hundred per cent seat is provided needing no further machiningoperation for producing a tight joint between itself and the part withwhich it is to cooperate. Furthermore, the steady rest seat pro-ventsany previous chatter or imperfections in the stem of the work or drivingparts of the machine from being transferred to and amplified on the seatof the work as was the case with prior processes.

What is claimed is:

l. The process of finishing the frustro-conical seat of a valve, or thelike, consisting in spinning the frustro-conical seating surface of thevalve against a contrageneric guide member engaging the major portion ofsaid seating surface and abrading said seating surface with a high speedgrinding member and positioning the operative portion of the grindingmember substantially co-planar with the valve supporting surface.

2. The process of perfecting the operative seat of a frustro-conicalvalve head consistingin providing a contragenerlc support member with aface for interfitting engagement with the face of the work, projecting agrinding member in inter rupting relation with said face of the supportand an operative portion forming a substantial continuation thereof,resiliently urging the valve against said combined seat whereby itspositioning is entirely determined by interengagement therewith,effecting a spinning of the valve on its seat and a rotation of thegrinding member at a speed in excess of .the peripheral speed effectedby spinning of the work whereby minute irregularities on the surface ofthe work are eliminated and a proper seating surface produced.

3. The process of producing a smooth seating face on a mushroom typevalve or the like, consisting in forming a support for the seating faceof the valve in part from an abrasive member and in part from anon-abrasive guide member, together engaging substantially the entireseating face, providing a clearance in the seating member for the valvestem whereby the member is supported entirely by engagement of itsseating face with said parts, urging the valve into engagement with saidseat, effecting a spinning of. the valve on said combined seat andsimultaneously effecting a high speed rotation of the abrasive portionof "the seat for removal of surface irregularities from the valve.

GEORGE W. BINNS.

